<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <h1>jquery的ajax请求</h1>
    <button id="btn">发起请求</button>
</body>

</html>
<script src="https://cdn.bootcdn.net/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script>


    btn.onclick = function () {


        getajax("post", "http://localhost:3000/students", { "username": 'zs' }, (res) => {
            console.log(res);
        })
    }


    function getajax(type, url, data, success) {

        let xhr = new XMLHttpRequest()
        xhr.open(type, url)
        xhr.setRequestHeader("Content-type", "application/json")
        xhr.send(JSON.stringify(data))

        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {

                let results = JSON.parse(xhr.responseText)

                // 处理results
                // 1、
                // 2、
                // 3、
                // 4、

                success(results)

            }
        }
    }




</script>